Publications:

The Aedes aegypti genome: a comparative perspective

The sequencing of the second mosquito genome, Aedes aegypti, in addition to Anopheles gambiae, is a major milestone that will drive molecular-level and genome-wide high-throughput studies of not only these but also other mosquito vectors of human pathogens. Here we overview the ancestry of the mosquito genes, list the major expansions of gene families that may relate to species adaptation processes, as exemplified by CYP9 cytochrome P450 genes, and discuss the conservation of chromosomal gene arrangements among the two mosquitoes and fruit fly. Many more invertebrate genomes are expected to be sequenced in the near future, including additional vectors of human pathogens (see http://www.vectorbase.org), and further comparative analyses will become increasingly refined and informative, hopefully improving our understanding of the genetic basis of phenotypical differences among these species, their vectorial capacity, and ultimately leading to the development of novel disease control strategies.

We present a draft sequence of the genome of Aedes aegypti, the primary vector for yellow fever and dengue fever, which at ~1.38 Gbp is ~5-fold larger in size than the genome of the malaria vector, Anopheles gambiae. Nearly 50% of the Aedes aegypti genome consists of transposable elements. These contribute to a ~4-6 fold increase in average gene length and the size of intergenic regions relative to Anopheles gambiae and Drosophila melanogaster. Nevertheless, chromosomal synteny is generally maintained between all three insects although conservation of orthologous gene order is higher (~2-fold) between the mosquito species than between either of them and fruit fly. An increase in genes encoding odorant binding, cytochrome P450 and cuticle domains relative to Anopheles gambiae suggests that members of these protein families underpin some of the biological differences between them.

Findings:

As expected, Aedes and Anopheles mosquitoes exhibit much higher conservation of ortholog identity and gene synteny than mosquito and fly or mosquito and hymenoptera comparisons:

11_orthologs

<protein_identity>

orth_in_synteny

Aaeg_Agam

6790

71.93%

77.54%

Aaeg_Flyb

6144

55.43%

31.41%

Agam_Flyb

6583

57.59%

34.95%

Aaeg_Amel

5648

52.70%

15.79%

Agam_Amel

6083

54.21%

18.58%

Amel_Flyb

6324

50.70%

13.43%

The estimation of number of synteny breaks in Aedes and Anophles lineages (as supported by the retained synteny to fly and honey bee) suggests about 2 times higher rate of genome shuffling in Aedes lineage. This observation might be explained by a higher transposon activity in Aedes known to facilitate inversions.

Comparison of gene family size dynamics showed most prominent expansions of Cytochrome P450, A10/OS-D pheromone-binding, insect cuticle, allergen related, HMG-I and HMG-Y gene families in Aedes as compared to only Cadherin in Anopheles. This analysis has also revealed some genes of Rhabdovirus origin. The expansions of various Zinc finger domains gene families is also may be of transposon/viral origin.